Various 3D television content and rendering devices are presently entering the consumer electronics market. Several technologies are available which produce viewer sensation of a 3D image, including anaglyphic based 3D utilizing glasses with two different color lenses (for example red and cyan); polarization based 3D utilizing glasses with lenses polarized in different directions (for example horizontal and vertical polarization); and alternate-frame sequencing based 3D utilizing glasses or headgear equipped with active-shutters which operate in synchronization with alternating picture frames. Autostereoscopic based displays which do not require any glasses or headgear (for example producing a 3D effect through the use of a Lenticular lens in the display device) have also been proposed, although at the current state of technology development these are generally effective only over a limited number of “sweet spot” viewer positions and/or for small display sizes.
Of the current technologies, many manufacturers of 3D TV rendering devices are opting for alternate-frame sequencing based 3D technology which utilizes active-shutter glasses. The shutter mechanism of the glasses may be electronic, for example using a transmissive LCD material, or may be mechanical. Shutter synchronization with the frames displayed by a 3D TV rendering device may be accomplished through a wired connection or wirelessly via an infrared or RF signal transmitted by the rendering device, playback device, or an external adapter supplied in conjunction with the active-shutter glasses; with the wireless signal generally preferred for user convenience.
In current implementations of the alternate-frame sequencing based 3D approach, many equipment manufacturers have developed proprietary signaling schemes, shutter timings, frame rates, and/or data formats for the synchronization signal transmitted to the active-shutter glasses (collectively referred to hereinafter as “signal format”). Accordingly, active-shutter glasses supplied with alternate-frame sequencing based 3D equipment of one manufacturer may not be compatible with, i.e., usable with, alternate-frame sequencing based 3D equipment of other manufactures. Because functional active-shutter glasses are a prerequisite for viewing alternate-frame sequencing based 3D content and because active-shutter glasses may be a relatively expensive accessory required for every individual viewer, this lack of compatibility may be perceived by consumers as a drawback.